JP6501638B2 - Electronic device - Google Patents

Description

  The present invention relates to a structure for radiating heat generated by an electronic component mounted on a printed circuit board through a heat transfer member embedded in the printed circuit board.

  In order to dissipate heat generated by electronic components mounted on a printed circuit board, various techniques have been proposed for embedding a heat transfer member in the printed circuit board.

  For example, in Patent Documents 1 to 3, a metal heat transfer member such as copper is embedded in the insulating layer of the printed board, and an electronic component that generates heat is mounted above the heat transfer member.

  In Patent Document 1, a wiring pattern is provided on the upper and lower surfaces and the inside of a printed circuit board, and an electronic component is mounted on the wiring pattern on the upper surface electrically connected to the heat transfer member. The lower surface of the heat transfer member is covered with an insulating layer having high thermal conductivity, and the heat dissipation member is provided to be in contact with the lower surface of the insulating layer. Thereby, the heat generated in the electronic component is transmitted to the heat dissipation member along the wiring pattern on the upper surface, the heat transfer member, and the insulating layer having high thermal conductivity, and is dissipated to the outside from the heat dissipation member.

  In Patent Document 2, the lower surface of the heat transfer member is exposed from the insulating layer of the printed circuit board, and the electronic component is mounted above the heat transfer member via the insulating layer having a high thermal conductivity and the wiring pattern. . As a result, the heat generated in the electronic component is dissipated to the outside from the exposed lower surface of the heat transfer member through the wiring pattern, the insulating layer having high thermal conductivity, and the heat transfer member.

  In Patent Document 3, the upper surface and the lower surface of the heat transfer member are exposed from the insulating layer of the printed circuit board, and the electronic component is mounted above the heat transfer member via the solder. In addition, a heat dissipation member is provided on the lower surface of the printed circuit board and the heat transfer member via a heat transfer material such as heat dissipation grease. Thus, the heat generated in the electronic component is transmitted to the heat dissipation member through the solder, the heat transfer member, and the heat transfer material, and is dissipated to the outside from the heat dissipation member.

  By the way, a heat-transfer member can be easily formed in a predetermined | prescribed shape by pierce | punching a metal plate in the thickness direction (press process), as disclosed by patent document 3, for example. In this case, one outer surface perpendicular to the thickness direction of the heat transfer member is a convex surface on which a curved surface portion (so-called "sagging") occurs at the edge, and the other surface perpendicular to the thickness direction of the heat transfer member The outer surface is a concave surface where protrusions (so-called "burrs") occur at its edges.

  In Patent Document 3, in order to prevent the solder from flowing out between the heat transfer member and the electronic component, the concave surface of the heat transfer member is exposed from the upper surface of the printed circuit board so as to face the electronic component. Also, the convex surface of the heat transfer member is exposed from the lower surface of the printed circuit board so as to face the heat dissipation member.

  Moreover, the outer shape is formed by punching out a metal plate like patent document 4-6 and a metal stiffener like patent document 7 in a thickness direction. Then, one outer surface perpendicular to the thickness direction is a convex surface having a sag, and the other outer surface is a concave surface having a burr.

  In Patent Documents 4 and 5, the concave surface of the metal substrate is disposed on the upper surface of the heat dissipation member via heat dissipation grease or solder. In patent document 7, the concave surface of the metal stiffener is installed on the upper surface of the wiring board via an adhesive. In Patent Document 6, a groove is provided on the upper surface of the metal substrate, and the metal substrate is punched in the groove to generate burrs in the groove. Then, a wiring pattern is provided on the top surface of the metal substrate other than the groove portion, and the electronic component is mounted.

JP 2007-36050 A JP, 2014-179416, A JP, 2014-63875, A Unexamined-Japanese-Patent No. 2007-88365 JP, 2008-311294, A JP 2007-36013 A JP 2001-44312 A

  For example, as shown in FIG. 6, the heat transfer member 53 is embedded in the printed circuit board 50, the electronic component 59 is disposed above the heat transfer member 53, and the lower surface of the heat transfer member 53 is from the insulating layer 52 of the printed circuit board 50. When exposed, the heat generated in the electronic component 59 can be dissipated to the lower side of the printed circuit board 50 through the insulating layer 51 and the heat transfer member 53 (see also Patent Documents 2 and 3). However, when the concave surface 53a with the burrs 53b of the heat transfer member 53 is directed to the electronic component 59 side, the burrs 53b bite into the insulating layer 51 between the electronic component 59 and the heat transfer member 53, and the insulating layer 51 It may be damaged, and the insulation performance and heat transfer performance of the printed circuit board 50 may be impaired.

  An object of the present invention is to efficiently dissipate heat generated by an electronic component mounted on a printed circuit board and to prevent the insulation performance of the printed circuit board from being impaired.

An electronic device according to the present invention includes a printed circuit board on which an electronic component that generates heat is mounted, and a heat dissipation member provided below the printed circuit board. The printed circuit board overlaps the mounting region with the first insulating layer provided with the mounting region of the electronic component and the wiring pattern on the upper surface, and the second insulating layer provided in contact with the lower surface of the first insulating layer. And a heat transfer member embedded in the second insulating layer . The heat transfer member is formed in a predetermined shape by cutting a metal plate. One outer surface perpendicular to the thickness direction of the heat transfer member is a convex surface having a curved surface portion (sagging) formed at an edge thereof, and is in contact with the lower surface of the first insulating layer. The other outer surface perpendicular to the thickness direction of the heat transfer member is a concave surface in which a protrusion (burr) is formed at the edge, and is exposed from the lower surface of the second insulating layer. An upper surface of the heat dissipation member is provided with a first pedestal projecting upward, and the first pedestal contacts a region of the concave surface of the heat transfer member inside the protrusion.

  According to the present invention, the heat transfer member is embedded in the second insulating layer of the printed circuit board, the electronic component is mounted above the heat transfer member via the first insulating layer, and the curved portion of the heat transfer member is formed. The second surface is brought into contact with the lower surface of the first insulating layer, and the concave surface on which the protrusion of the heat transfer member is formed is exposed from the lower surface of the second insulating layer. Therefore, the convex surface of the heat transfer member is brought into close contact with the first insulating layer, and the heat generated in the electronic component is easily conducted to the heat transfer member through the first insulating layer, and the concave surface of the heat transfer member The heat can be dissipated efficiently to the outside. In addition, since the protruding portion of the heat transfer member is disposed toward the outside of the printed circuit board, the first insulating layer is not damaged by the protruding portion, and the electronic component on the printed circuit board, the wiring pattern, and the heat transfer member It is possible to prevent the insulation performance of the first insulating layer which insulates from being impaired.

In the present invention, in the electronic device , the thermal conductivity of the first insulating layer is higher than the thermal conductivity of the second insulating layer, and the thermal conductivity of the heat transfer member is higher than the thermal conductivity of the first insulating layer. It may be high.

Further, in the present invention, in the electronic device , the second insulating layer has a laminated structure, and the first inner layer between the first insulating layer and the second insulating layer, and the second inside the second insulating layer. Wiring patterns may be provided in the inner layer, respectively. In this case, the wiring pattern of the inner layer is insulated with respect to the heat transfer member.

Further, in the present invention, in the electronic device , the mounting region of the electronic component and the wiring pattern may be provided on the lower surface of the second insulating layer. In this case, the mounting area on the lower surface and the wiring pattern are insulated with respect to the heat transfer member.

Further, in the present invention, the electronic device may further include a through conductor which penetrates the first insulating layer and the second insulating layer and connects the wiring patterns in the both insulating layers. In this case, the through conductor is insulated with respect to the heat transfer member.

  In the present invention, in the electronic device, in the upper surface of the heat dissipation member, an electronic component and a wiring pattern provided on the lower surface of the second insulating layer of the printed circuit board, and a recess avoiding the protrusion of the concave surface of the heat transfer member. Is preferably provided.

  In the present invention, in the electronic device, through holes are provided in the mounting area of the printed circuit board, the wiring pattern, and a non-overlapping area not overlapping the heat transfer member, and the upper surface of the heat dissipation member is separated from the first pedestal. Providing a second pedestal projecting into the second pedestal, the second pedestal contacting a non-overlapping area of the printed circuit board, and providing a screwing hole in the second pedestal so as to communicate with the through hole; penetrating the screwing member from above the printed circuit board The printed circuit board may be fixed on the heat dissipation member by penetrating the hole and screwing the screw hole.

  According to the present invention, it is possible to efficiently dissipate the heat generated by the electronic component mounted on the printed circuit board and to prevent the insulation performance of the printed circuit board from being impaired.

It is the figure which showed the upper surface layer of the printed circuit board of embodiment of this invention. It is the figure which showed the AA cross section of FIG. It is the figure which showed the inner layer of the printed circuit board of FIG. It is the figure which showed the lower surface layer of the printed circuit board of FIG. It is the figure which showed the manufacturing process of the printed circuit board of FIG. It is the figure which showed the continuation of the manufacturing process of FIG. 5A. It is a figure for demonstrating the problem by the burr | flash of a heat-transfer member. It is a figure for demonstrating the other problem by the burr | flash of a heat-transfer member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same parts and corresponding parts are given the same reference numerals.

  First, the structures of the printed circuit board 10 and the electronic device 100 according to the embodiment will be described with reference to FIGS. 1 to 4.

  FIG. 1 is a view showing the upper surface layer L1 on the upper surface of the printed circuit board 10. As shown in FIG. FIG. 2 is a view showing a cross section AA of FIG. FIG. 3 is a view showing the inner layers L2, L3 and L4 inside the printed circuit board 10. As shown in FIG. FIG. 4 is a view showing a layer L5 shown in the following table on the lower surface of the printed circuit board 10. 1 and 3 show a state seen from above the printed circuit board 10, and FIG. 4 shows a state seen from below the printed circuit board 10. Further, in the respective drawings, only the printed board 10 and a part of the electronic device 100 are illustrated for the sake of convenience.

  The electronic device 100 includes, for example, a DC-DC converter mounted on an electric vehicle or a hybrid car. The electronic device 100 includes a printed circuit board 10, electronic components 9a to 9j, and a heat sink 4.

As shown in FIG. 2, the printed circuit board 10 is a multilayer board in which surface layers L1 and L5 are provided on the upper surface and the lower surface, respectively, and a plurality of inner layers L2, L3 and L4 are provided inside. The printed circuit board 10 includes a first insulating layer 1, a second insulating layer 2, the metal core 3, wiring pattern 5A～5w, and the through-hole 6a~6e like are provided (FIGS. 1, 3, and 4 also reference).

  The first insulating layer 1 is composed of a high thermal conductivity prepreg 1a. The high thermal conductivity prepreg 1a is, for example, a prepreg having high thermal conductivity and insulation, which is produced by mixing alumina into epoxy or the like. The first insulating layer 1 is formed in a flat plate shape having a predetermined thickness (about 100 μm).

  An upper surface layer L1 is provided on the upper surface of the first insulating layer 1 exposed to the outside. As shown in FIG. 1, mounting areas Ra to Rg of the electronic components 9 a to 9 g and wiring patterns 5 a to 5 i are provided in the upper surface layer L1.

  Wiring pattern 5a-5i consists of copper foil which has conductivity and heat conductivity. Some of the wiring patterns 5a to 5i function as lands to which the electronic components 9a to 9g are soldered.

  FETs (field effect transistors) 9a and 9b are mounted on the mounting areas Ra and Rb, respectively. Discrete components 9 c are mounted in the mounting area Rc. Chip capacitors 9 d to 9 g are mounted on the mounting regions Rd to Rg, respectively.

  The FETs 9a and 9b are surface mount electronic components that generate a large amount of heat. The source terminal s1 of the FET 9a is soldered on the wiring pattern 5a. The gate terminal g1 of the FET 9a is soldered on the wiring pattern 5b. The drain terminal d1 of the FET 9a is soldered on the wiring pattern 5c. The source terminal s2 of the FET 9b is soldered on the wiring pattern 5c. The gate terminal g2 of the FET 9b is soldered on the wiring pattern 5d. The drain terminal d2 of the FET 9b is soldered to the wiring pattern 5e.

  The discrete component 9c is an electronic component provided with lead terminals t1 and t2 (FIG. 1) penetrating the printed circuit board 10 as shown in FIG. The main body of the discrete component 9 c is mounted on the upper surface of the first insulating layer 1. The lead terminals t1 and t2 of the discrete component 9c are soldered after being inserted into the through holes 6c and 6d, respectively.

  The chip capacitors 9 d to 9 g are surface mount electronic components. As shown in FIG. 1, the chip capacitor 9d is soldered on the wiring patterns 5b and 5h. The chip capacitors 9e are soldered on the wiring patterns 5e and 5f. The chip capacitors 9f are soldered on the wiring patterns 5d and 5i. The chip capacitor 9g is soldered on the wiring patterns 5e and 5g.

  As shown in FIG. 2, the second insulating layer 2 is provided in contact with the lower surface of the first insulating layer 1. The second insulating layer 2 is configured by bonding the copper-clad laminate 2 a to the upper and lower surfaces of a conventional prepreg 2 b impregnated with a synthetic resin. The normal prepreg 2b is a prepreg which is a material of a general printed circuit board. The copper-clad laminate 2 a is obtained by bonding copper foils to upper and lower surfaces of a plate made of a synthetic resin such as epoxy containing glass fiber. Therefore, the second insulating layer 2 is formed in a flat plate shape having a thickness greater than that of the first insulating layer 1 and has a laminated structure.

  Further, the second insulating layer 2 has two types of insulating portions: a normal prepreg 2 b and a core (made of synthetic resin) 2 c of the copper-clad laminate 2 a. The materials of the insulating portions 2 b and 2 c are different, and the thickness of each of the insulating portions 2 b and 2 c is equal to the thickness of the first insulating layer 1. As another example, the thicknesses of the insulating portions 2b and 2c may be different.

  An inner layer L2 is provided between the first insulating layer 1 and the second insulating layer 2 using the copper foil portion of each copper-clad laminate 2a of the second insulating layer 2, and the inner layer L3, L4 is provided, and a lower layer L5 shown below is provided on the lower surface of the second insulating layer 2.

  As shown in FIG. 3, in the inner layers L2 to L4, wiring patterns 5j to 5n, 5j 'to 5n', 5j "to 5n" are provided. Each of the wiring patterns 5j to 5n, 5j 'to 5n', 5j "to 5n" is made of a copper foil having conductivity and thermal conductivity.

  In this example, the wiring patterns 5j, 5k, 51, 5m, 5n of the inner layer L2, the wiring patterns 5j ', 5k', 5l ', 5m', 5n 'of the inner layer L3, and the wiring patterns 5j ", 5k of the inner layer L4. ", 5l", 5m "and 5n" have the same shape, respectively. As another example, the shapes of the wiring patterns of the inner layers L2, L3, and L4 may be made different. The inner layers L3 and L4 are examples of the "first inner layer" of the invention, and the inner layers L3 and L4 are examples of the "second inner layer" of the present invention.

  As shown in FIG. 4, mounting regions Rh to Rj of the electronic components 9 h to 9 j and wiring patterns 5 o to 5 w are provided in the layer L5 in the following table. The wiring patterns 5o to 5w are made of a copper foil having conductivity and thermal conductivity. Parts of the wiring patterns 5p, 5q, 5s, 5t, 5v, 5w function as lands to which the electronic components 9h to 9j are soldered.

  The electronic components 9h to 9j are surface mount chip capacitors. The chip capacitor 9h is soldered on the wiring patterns 5p and 5q. The chip capacitor 9i is soldered on the wiring patterns 5t and 5s. The chip capacitors 9j are soldered on the wiring patterns 5v and 5w.

  As shown in FIG. 2, the metal core 3 is embedded in the second insulating layer 2. The metal core 3 is in contact with the lower surface of the first insulating layer 1 and is provided in the upper surface layer L1 with a plurality of mounting areas Ra, Rb, Rd, Rf and a plurality of wiring patterns 5a-5e, 5h, 5i (FIG. 1). It is widely provided so that it overlaps with all or part and the upper and lower sides. That is, the metal core 3 is covered from the upper side by the first insulating layer 1 and is covered by the second insulating layer 2 on all sides.

  The metal core 3 is made of a metal such as copper having conductivity and heat conductivity. The metal core 3 is formed in a rectangular shape when viewed from above or below as shown in FIGS. 1 and 4.

  The metal core 3 is formed in a predetermined shape by punching a metal plate in the thickness direction with a press. Therefore, as shown in FIG. 2, a curved surface portion (hereinafter referred to as "sagging") 3d is formed at the edge of one outer surface 3c perpendicular to the thickness direction (vertical direction in FIG. 2) of metal core 3. It becomes a convex surface. Further, the other outer surface 3a perpendicular to the thickness direction of the metal core 3 is a concave surface having a protrusion (hereinafter referred to as "burr") 3b formed at the edge thereof.

  The convex surface 3 c of the metal core 3 is in contact with the lower surface of the first insulating layer 1. The concave surface 3 a and the burr 3 b of the metal core 3 are exposed from the lower surface of the second insulating layer 2. The metal core 3 is an example of the “heat transfer member” in the present invention.

  The thermal conductivity of the metal core 3 is higher than the thermal conductivity of the first insulating layer 1. The thermal conductivity of the first insulating layer 1 is higher than the thermal conductivity of the second insulating layer 2. Specifically, for example, while the thermal conductivity of the second insulating layer 2 is 0.3 to 0.5 W / mK (mK: meter · kelvin), the thermal conductivity of the first insulating layer 1 is It is 3 to 5 W / mK. When the metal core 3 is made of copper, the thermal conductivity of the metal core 3 is about 400 W / mK.

  The first insulating layer 1 is interposed between the metal core 3 and the wiring patterns 5a to 5e, 5h, 5i above the metal core 3 and the electronic components 9a, 9b, 9d, 9f in the upper surface layer L1. . Therefore, the wiring patterns 5 a to 5 e, 5 h, 5 i and the electronic components 9 a, 9 b, 9 d, 9 f are insulated with respect to the metal core 3.

  In each of the inner layers L2 to L4, a prepreg of the second insulating layer 2 is interposed between the metal cores 3 and the wiring patterns 5j to 5n, 5j 'to 5n', 5j "to 5n" in the vicinity of the metal core 3. ing. For this reason, the wiring patterns 5j to 5n, 5j 'to 5n', 5j "to 5n" are insulated with respect to the metal core 3.

  In the layer L5 in the following table, the wiring patterns 5o, 5p, 5r, 5s, 5u near the metal core 3 and the metal core 3 are separated by a predetermined insulation distance. Therefore, the electronic components 9 h and 9 i mounted on the wiring patterns 5 o, 5 p, 5 r, 5 s and 5 u and the wiring patterns 5 p and 5 s are insulated with respect to the metal core 3.

  The through holes 6a to 6e pass through the first insulating layer 1, the second insulating layer 2, and the wiring patterns in the both insulating layers 1 and 2 (FIG. 2). The inner surfaces of the through holes 6a to 6e are plated with copper or solder. Through holes 6a to 6e connect wiring patterns in different layers L1 to L5. Through holes 6 a to 6 e and metal core 3 are insulated by insulating layers 1 and 2. The through holes 6a to 6e are examples of the "through conductor" in the present invention.

  Specifically, as shown in FIGS. 1 to 4, through holes 6a are formed of insulating patterns 1 and 2, wiring pattern 5a of upper surface layer L1, and wiring patterns 5j, 5j ′, 5j ′ ′ of inner layers L2 to L4, and layer L5 of the following table. A plurality of through holes 6a are provided so as to penetrate through the wiring patterns 5o, and each of the through holes 6a connects the wiring patterns 5a, 5j, 5j ', 5j ", 5o.

  A plurality of through holes 6b are provided so as to penetrate the wiring patterns 5e of the insulating layers 1 and 2, and the upper surface layer L1, the wiring patterns 5m, 5m ', 5m "of the inner layers L2 to L4 and the wiring pattern 5s of the following layer L5. Each through hole 6 b connects the wiring patterns 5 e, 5 m, 5 m ′, 5 m ′ ′, 5 s.

  The through holes 6c are provided to penetrate the wiring patterns 5e of the insulating layers 1 and 2 and the upper surface layer L1, the wiring patterns 5m, 5m ', 5m "of the inner layers L2 to L4 and the wiring pattern 5s of the following layer L5. One lead terminal t1 of the discrete component 9c is soldered to the through hole 6c, and the lead terminal t1 is connected to the wiring patterns 5e, 5m, 5m ', 5m ", 5s.

  The through holes 6d are provided to penetrate the wiring patterns 5f of the insulating layers 1 and 2 and the upper surface layer L1, the wiring patterns 5n, 5n ', 5n "of the inner layers L2 to L4 and the wiring pattern 5r of the below-described layer L5. The other lead terminal t2 of the discrete component 9c is soldered to the through hole 6d, and the lead terminal t2 is connected to the wiring patterns 5f, 5n, 5n ', 5n ", 5r.

  The through holes 6e are provided to penetrate the wiring patterns 5h of the insulating layers 1 and 2 and the upper surface layer L1, the wiring patterns 5k, 5k 'and 5k "of the inner layers L2 to L4, and the wiring pattern 5p of the below-described layer L5. The through holes 6e connect the wiring patterns 5h, 5k, 5k ', 5k ", 5p.

  As shown in FIG. 2, a heat sink 4 is provided below the second insulating layer 2 and the metal core 3 of the printed circuit board 10. The heat sink 4 is made of metal such as aluminum and dissipates heat generated by the printed circuit board 10 to the outside to cool the printed circuit board 10. The heat sink 4 is an example of the “heat dissipation member” in the present invention.

  A first pedestal 4 a and a second pedestal 4 b are formed on the upper surface of the heat sink 4 so as to protrude upward. The top surfaces of the pedestals 4 a and 4 b are parallel to the surface of the printed circuit board 10. When viewed from above the printed circuit board 10, as shown in FIG. 1, the area of the first pedestal 4a is smaller than the area of the metal core 3.

  Screwing holes 4 h are formed in the second pedestal 4 b in parallel with the thickness direction (vertical direction in FIG. 2) of the printed circuit board 10. Through holes 7 are provided in non-overlapping regions P which do not overlap the mounting regions Ra to Rj and the wiring patterns 5a to 5w in the respective insulating layers 1 and 2. When viewed from above the printed circuit board 10, as shown in FIG. 1, the area of the second pedestal 4b is slightly smaller than the area of each non-overlapping region P. Further, the area of the second pedestal 4 b is larger than the area of the through hole 7 (see FIGS. 3 and 4).

  When the second pedestal 4 b is brought into contact with the non-overlapping region P on the lower surface of the printed circuit board 10, the through hole 7 and the screwing hole 4 h communicate with each other. Then, when the screw 8 is penetrated from above the first insulating layer 1 to the through hole 7 and screwed into the screwing hole 4 h, as shown in FIG. 2, the second pedestal 4 b is formed on the lower surface of the second insulating layer 2. It is fixed. The printed circuit board 10 is fixed on the heat sink 4 by providing a plurality of such screwing points. As shown in FIG. 1, the area of the head of the screw 8 is smaller than the area of the non-overlapping region P. The screw 8 is an example of the “screwing member” in the present invention.

  As shown in FIG. 2, in the fixed state of the heat sink 4 and the printed circuit board 10, the upper surface of the first pedestal 4 a contacts the area on the concave surface 3 a of the metal core 3 inside the burr 3 b.

  For example, thermal grease (not shown) having high thermal conductivity may be applied to the upper surface of the first pedestal 4a. Thereby, the adhesion between the upper surface of the first pedestal 4 a and the concave surface 3 a of the metal core 3 is enhanced, and the thermal conductivity from the metal core 3 to the heat sink 4 is enhanced.

  In order to avoid the electronic components 9h to 9j and the wiring patterns 5o to 5w provided on the lower surface of the second insulating layer 2 and the burrs 3b of the concave surface 3a of the metal core 3 around the first pedestal 4a on the heat sink 4. , The recess 4c is provided.

  Next, a method of manufacturing the printed circuit board 10 will be described with reference to FIGS. 5A and 5B.

  5A and 5B are diagrams showing the manufacturing process of the printed circuit board 10. As shown in FIG. In FIG. 5A and FIG. 5B, each part of the printed circuit board 10 is simplified and shown for convenience.

  In FIG. 5A, copper foils on the upper and lower surfaces of one of the two copper clad laminates 2a among the two copper clad laminates 2a are etched, etc. to form the wiring patterns 5j to 5n and 5j 'of the inner layers L2 and L3. 5n '(not shown in FIGS. 5A and 5B). In addition, the copper foil on the upper surface of the other copper clad laminate 2a is etched or the like to form the wiring patterns 5j "to 5n" (symbols omitted in FIGS. 5A and 5B) of the inner layer L4 (FIG. 1)).

  Next, through holes 2h for inserting the metal core 3 into the respective copper-clad laminates 2a are formed ((2) in FIG. 5A). Further, through holes 2 h ′ for inserting the metal core 3 are also formed in the normal prepreg 2 b ((3) in FIG. 5A).

  Also, a highly thermal conductive prepreg 1a having a predetermined thickness and a copper foil 5 having a predetermined thickness for attachment to the upper surface of the prepreg 1a are prepared ((4) in FIG. 5A).

  Further, a metal plate 3 ′ such as a copper plate is cut by a press 11 and punched in the thickness direction to form a metal core 3 of a predetermined shape ((5), (5 ′) of FIG. 5A). At that time, the upper surface 3a of the metal core 3 with which the upper mold 11u of the press 11 abuts is a concave surface in which the burr 3b is generated at the edge thereof. Further, the lower surface 3c of the metal core 3 with which the lower die 11d of the press machine 11 abuts is a convex surface in which a sag 3d is produced at the edge thereof. The lower surface 3c corresponds to the "one outer surface" in the present invention, and the upper surface 3a corresponds to the "other outer surface" in the present invention.

  As another example, the metal core may be formed by cutting a metal plate into a predetermined shape by wire cutting. Also in this case, one outer surface perpendicular to the thickness direction of the metal core is a convex surface in which sagging has occurred on the edge. Further, the other outer surface perpendicular to the thickness direction of the metal core is a concave surface in which burrs are generated at the edge.

  Next, as shown in (6) of FIG. 5B, one copper-clad laminate 2a, a normal prepreg 2b and the other copper-clad laminate 2a are sequentially stacked from the bottom, and these through holes 2h and 2h ' Insert the metal core 3 into the At this time, the metal core 3 is inserted from the convex surface 3c to the through holes 2h and 2h 'from the lower side of one copper clad laminate 2a. Then, the high thermal conductivity prepreg 1a and the copper foil 5 are sequentially stacked on top of them, and then crimped in the vertical direction (the thickness direction of each member) while applying heat.

  As a result, the synthetic resin of each of the prepregs 2b and 1a melts, enters the gap between the members, and is adhered to each other to form the second insulating layer 2, the first insulating layer 1, and the inner layers L2 to L4 ( (6 ') of FIG. 5B). The convex surface 3 c of the metal core 3 is in contact with the lower surface of the first insulating layer 1, and all the side surfaces of the metal core 3 are in contact with the second insulating layer 2. Furthermore, the concave surface 3 a and the burr 3 b of the metal core 3 are exposed from the lower surface of the second insulating layer 2.

  Next, holes are made in predetermined places, and the inner surfaces of the holes are plated to form through holes 6a to 6e (portion 6 in FIG. 5B) ((7) in FIG. 5B). Next, the copper foil 5 at the top is etched or the like to form the wiring patterns 5a to 5i (symbols are omitted in FIG. 5B) of the upper surface layer L1 on the upper surface of the first insulating layer 1. Further, the copper foil at the lowermost portion is etched or the like to form wiring patterns 5o to 5w (symbols are omitted in FIG. 5B) of the layer L5 in the following table on the lower surface of the second insulating layer 2. ((8) in FIG. 5B). At this time, mounting areas Ra to Rj (FIG. 1 and FIG. 4) of the electronic component are also provided in both surface layers L1 and L5.

  Thereafter, the exposed upper surface of the first insulating layer 1, the wiring patterns 5a to 5i, the lower surface of the second insulating layer 2, and the wiring patterns 5o to 5w are subjected to surface treatment such as resist or silk (see FIG. FIG. 5B (9)). Then, the extra end of each of the insulating layers 1 and 2 is cut or the like to process the outer shape ((10) in FIG. 5B). Thus, the printed circuit board 10 is formed.

  According to the above embodiment, the metal core 3 is embedded in the second insulating layer 2 of the printed circuit board 10, and the electronic component 9a is formed above the metal core 3 via the first insulating layer 1 and the wiring patterns 5a to 5e, 5h and 5i. 9b, 9d, 9f are implemented. Further, the convex surface 3 c on which the sag 3 d of the metal core 3 is formed is brought into contact with the lower surface of the first insulating layer 1, and the concave surface 3 a on which the burrs 3 b of the metal core 3 are formed is exposed from the lower surface of the second insulating layer 2. ing. Then, the upper surface of the first pedestal 4 a of the heat sink 4 is brought into contact with the concave surface 3 a of the metal core 3.

  For this reason, the convex surface 3c of the metal core 3 is brought into close contact with the first insulating layer 1, and the heat generated in the electronic components 9a, 9b, 9d, 9f is generated by the wiring patterns 5a-5e, 5h, 5i and the first insulating layer. It can be made easy to transmit to the metal core 3 via 1. Then, the heat can be transmitted from the concave surface 3 a of the metal core 3 to the heat sink 4, and can be efficiently dissipated from the heat sink 4 to the outside.

  In addition, since the burr 3b of the metal core 3 is disposed toward the outside of the printed circuit board 10, the burr 3b does not damage the first insulating layer 1. As a result, the insulation performance of the first insulating layer 1 which insulates the metal core 3 from the electronic components 9a, 9b, 9d, 9f and the wiring patterns 5a to 5e, 5h, 5i on the printed circuit board 10 is prevented from being impaired. be able to.

  Further, since the first insulating layer 1 is provided on the upper surfaces of the metal core 3 and the second insulating layer 2, the plurality of electronic components 9a, 9b, 9d, 9f are provided above the metal core 3 in a state insulated from the metal core 3. It can be easily implemented. Further, the plurality of wiring patterns 5a to 5e, 5h and 5i can be easily formed above the metal core 3 in a state of being insulated from the metal core 3. Therefore, it is possible to easily form an electric circuit on the upper surface of the printed circuit board 10 and to increase the mounting density of the printed circuit board 10. Further, the heat generated by the plurality of electronic components 9a, 9b, 9d, 9f can be transmitted to the heat sink 4 through the first insulating layer 1 and the metal core 3, and can be efficiently dissipated collectively.

  In the above embodiment, the thermal conductivity of the first insulating layer 1 is higher than the thermal conductivity of the second insulating layer 2, and the thermal conductivity of the metal core 3 is higher than the thermal conductivity of the first insulating layer 1. . Therefore, the heat generated by the electronic components 9 a, 9 b, 9 d, 9 f mounted above the metal core 3 can be easily transmitted to the metal core 3 via the first insulating layer 1. Then, heat can be transmitted to the heat sink 4 from the concave surface 3 a of the metal core 3 exposed from the second insulating layer 2, and the heat can be dissipated more efficiently from the heat sink 4 to the outside.

  In the above embodiment, the wiring patterns 5j to 5n and 5j are respectively formed on the inner layer L2 between the first insulating layer 1 and the second insulating layer 2 and the inner layers L3 and L4 inside the second insulating layer 2. '-5 n', 5 j ''-5 n '' are provided. The wiring patterns 5j to 5n, 5j 'to 5n', 5j "to 5n" are insulated from the metal core 3 by the insulating layers 1 and 2, respectively. Therefore, after the heat generated by the electronic components 9a to 9g mounted on the upper surface of the first insulating layer 1 is transmitted to the first insulating layer 1 and the metal core 3, the wiring patterns 5j to 5n and 5j of the inner layers L2 to L4 are transmitted. It can be diffused to the whole printed circuit board 10 by '̃5 n ′, 5 j ′ ′ ̃ 5 n ′ ′. Further, the metal core 3 is inserted into the through holes 2 h and 2 h ′ of the second insulating layer 2 from the convex surface 3 c side without the burrs 3 b so that the through holes 2 h of the second insulating layer 2 can be formed by the burrs 3 b at the time of fitting. The side wall portion 2h 'is not damaged, and the insulation performance of the second insulating layer 2 can be prevented from being impaired.

  In the above embodiment, mounting areas Rh to Rj of the electronic components 9 h to 9 j and wiring patterns 5 o to 5 w are provided on the lower surface of the second insulating layer 2. The electronic components 9 h to 9 j and the wiring patterns 5 o to 5 w are insulated with respect to the metal core 3. Therefore, it is possible to radiate the heat generated in the electronic components 9 a to 9 g on the upper surface and diffused to the entire printed circuit board 10 and the heat generated on the electronic components 9 h to 9 j on the lower surface to the lower part of the printed substrate 10. In addition, an electrical circuit can be easily formed on the lower surface of the printed circuit board 10 to further increase the mounting density of the printed circuit board 10. Furthermore, even if the concave surface 3a with the burr 3b of the metal core 3 is exposed from the lower surface of the second insulating layer 2, the electronic components 9h to 9j and the wiring patterns 5o to 5w on the lower surface of the second insulating layer 2 and the metal core 3 can be reliably isolated.

  Further, in the above embodiment, the wiring patterns 5a, 5e, 5f, 5h, 5j, 5k, 5m, 5n, 5j ', 5k provided on the upper surface of the first insulating layer 1 and the inside or lower surface of the second insulating layer 2. ', 5m', 5n ', 5j ", 5k", 5m ", 5n", 5o, 5p, 5r, 5s are connected by through holes 6a to 6e. Therefore, on the upper surface of the printed circuit board 10, the heat generated in the electronic components 9a to 9g and transmitted to the wiring patterns 5a, 5e, 5f, 5h is transmitted through the through holes 6a to 6e to the internal wiring patterns 5j, 5k, It can be diffused to the entire printed circuit board 10 by transmitting to 5 m, 5 n, 5 j ', 5 k', 5 m ', 5 n', 5 j ", 5 k", 5 m ", 5 n". Further, the heat is also transmitted to the wiring patterns 5o, 5p, 5r and 5s on the lower surface to be dissipated downward from the surface of the wiring patterns 5o, 5p, 5r and 5s or dissipated through the metal core 3 and the heat sink 4. can do. Further, since the through holes 6a to 6e are provided at positions not overlapping with the metal core 3 vertically, the through holes 6a to 6e and the metal core 3 can be insulated by the insulating layers 1 and 2.

  For example, as shown in FIG. 7, when the heat transfer member 53 is to be placed on the upper surface of the flat heat sink 54 not having a pedestal, the heat transfer member 53 is supported on the heat sink 54 by the burrs 53b and a concave surface A gap 55 is generated between the region inside the burr 53 b of 53 a and the upper surface of the heat sink 54. For this reason, after the heat generated in the electronic component 59 above the heat transfer member 53 passes through the insulating layer 51, it is difficult to transfer the heat from the heat transfer member 53 to the heat sink 54, and the heat radiation performance is impaired.

  However, in the above embodiment, as shown in FIG. 2, the upper surface of the first pedestal 4 a of the heat sink 4 is in contact with the area inside the burr 3 b of the concave surface 3 a of the metal core 3. There is no gap between 4a. Therefore, after passing the heat generated in the electronic components 9a, 9b, 9d and the like above the metal core 3 through the first insulating layer 1, the metal core 3 can be easily conducted from the metal core 3 to the heat sink 4 to efficiently dissipate the heat. Can.

  In the above embodiment, the depressions 4c are provided on the heat sink 4, and the electronic components 9h to 9j and the wiring patterns 5o to 5w provided on the lower surface of the second insulating layer 2 and the burrs 3b of the concave surface 3a of the metal core 3 are provided. Avoid interference with Therefore, the electronic components 9 h to 9 j and the wiring patterns 5 o to 5 w can be insulated with respect to the heat sink 4. In addition, since the burr 3b does not contact the heat sink 4, no gap is generated between the metal core 3 and the heat sink 4, and the heat radiation performance can be prevented from being impaired.

  Furthermore, in the above embodiment, the upper surface of the second pedestal 4b of the heat sink 4 is brought into contact with the mounting regions Ra to Rj of the printed circuit board 10, the wiring patterns 5a to 5w, and the non-overlapping region P not overlapping the metal core 3 The printed circuit board 10 is screwed to the two pedestals 4b. Therefore, the printed circuit board 10 can be fixed on the heat sink 4 while insulating the electronic components 9 a to 9 j, the wiring patterns 5 a to 5 w, and the through holes 6 a to 6 e provided on the printed circuit board 10 from the heat sink 4 .

  In the present invention, various embodiments can be adopted other than those described above. For example, in FIG. 2, for convenience of explanation, the burrs 3b and the drips 3d are drawn exaggerating the actual ones, but the burrs 3b and the drips 3d are not limited to those which are large enough to be visible, and are invisible It may be minute.

Further, in the above embodiment, in order to electrically connect the upper surface of the first insulating layer 1 of the printed circuit board 10 and the wiring pattern on the inside and the lower surface of the second insulating layer 2, an example in which the through holes 6a to 6e are provided is shown. However, the present invention is not limited to this. Besides this, for example, conductors such as copper terminals or pins may be provided to penetrate the printed circuit board to connect the wiring patterns of different layers.

  In the above embodiments, the metal core 3 has a rectangular shape when viewed from above, but the present invention is not limited to this. According to the arrangement position and the shape of the electronic component that generates heat, it is viewed from above The shape of the metal core can be any shape.

  Moreover, although the example which used the heat sink 4 as a thermal radiation member was shown in the above embodiment, it may replace with this and may use the radiator of air cooling type or water cooling type, or the radiator using a refrigerant | coolant, etc. . Further, not only the metal heat dissipating member but also a heat dissipating member formed of a resin having high thermal conductivity may be used.

  Moreover, although the example which used the screw 8 as a screwing member was shown in the above embodiment, you may use a screw, a bolt, etc. instead of this. In addition, the heat dissipation member may be attached to the lower side of the printed circuit board by another fixing tool.

  Moreover, although the example which applied this invention to the printed circuit board 10 in which two surface layer L1, L5 and three inner layers L2-L4 were provided was mentioned in the above embodiment, this invention has a wiring pattern etc. only in the upper surface. The present invention can also be applied to a single-layer printed circuit board provided with the above conductor, and a printed circuit board provided with the conductor provided in two or more layers.

  Furthermore, in the above embodiments, a DC-DC converter mounted on an electric car or a hybrid car has been described as an example of the electronic device 100. However, in the present invention, a printed circuit board, an electronic component that generates heat, and a heat dissipation member Can be applied to other electronic devices.

1 first insulating layer 2 second insulating layer 3 metal core (heat transfer member)
3 'metal plate 3a concave surface 3b burr (protrusion)
3c convex surface 3d sag (curved surface)
4 Heat sink (heat dissipation member)
4a 1st pedestal 4b 2nd pedestal 4c hollow 4h Screw holes 5a to 5i Wiring patterns on the upper surface layer 5j to 5n, 5j 'to 5n', 5j "to 5n" Inner layer wiring pattern 5o to 5w Wiring layer pattern 6a in the below table layer 6e through hole (through conductor)
7 through hole 8 screw (screwing member)
9a, 9b FET (Electronic Component)
9c Discrete parts (electronic parts)
9d to 9j Chip Capacitors (Electronic Components)
10 printed circuit board 100 electronic device L2 inner layer (first inner layer)
L3, L4 inner layer (second inner layer)
P non-overlap area Ra to Rj implementation area

Claims (7)

An electronic device comprising: a printed circuit board on which an electronic component that generates heat is mounted; and a heat dissipation member provided below the printed circuit board,
The printed circuit board is
A first insulating layer in which the electronic component mounting region and the wiring pattern is provided on the upper surface,
A second insulating layer provided in contact with the lower surface of the first insulating layer;
And a heat transfer member embedded in said second insulating layer so as to overlap vertically with the mounting region,
The heat transfer member is formed into a predetermined shape by cutting a metal plate,
One outer surface perpendicular to the thickness direction of the heat transfer member is a convex surface having a curved surface portion formed at an edge thereof, and is in contact with the lower surface of the first insulating layer,
The other outer surface perpendicular to the thickness direction of the heat transfer member is a concave surface having a protrusion formed at an edge thereof and exposed from the lower surface of the second insulating layer .
A first pedestal projecting upward is provided on the top surface of the heat dissipation member,
The electronic device according to claim 1, wherein the first pedestal is in contact with a region on the concave surface of the heat transfer member that is inside the protrusion . In the electronic device according to claim 1 ,
The thermal conductivity of the first insulating layer is higher than the thermal conductivity of the second insulating layer,
The thermal conductivity of the heat transfer member is higher than the thermal conductivity of the first insulating layer, an electronic device, characterized in that. In the electronic device according to claim 1 or 2 ,
The second insulating layer has a laminated structure,
Wiring patterns are provided on a first inner layer between the first insulating layer and the second insulating layer, and a second inner layer inside the second insulating layer, respectively.
The said wiring pattern of a said 1st inner layer and a said 2nd inner layer is insulated with respect to the said heat-transfer member, The electronic device characterized by the above-mentioned. The electronic device according to any one of claims 1 to 3 .
A mounting area of the electronic component and a wiring pattern are provided on the lower surface of the second insulating layer,
The said mounting area | region of the lower surface of the said 2nd insulating layer and the said wiring pattern are insulated with respect to the said heat-transfer member, The electronic device characterized by the above-mentioned. In the electronic device according to claim 4 ,
The semiconductor device further includes a through conductor penetrating the first insulating layer and the second insulating layer and connecting the wiring patterns in the both insulating layers.
The said penetration conductor is insulated with respect to the said heat-transfer member, The electronic device characterized by the above-mentioned. The electronic device according to any one of claims 1 to 5 .
An electronic component and a wiring pattern provided on the lower surface of the second insulating layer of the printed circuit board, and a recess for avoiding the protrusion of the concave surface of the heat transfer member are provided on the upper surface of the heat dissipation member. Electronic device characterized by The electronic device according to any one of claims 1 to 6 .
Through holes are provided in the mounting area of the printed circuit board, the wiring pattern, and a non-overlapping area not overlapping the heat transfer member.
A second pedestal protruding upward is provided on the upper surface of the heat dissipation member separately from the first pedestal,
The second pedestal contacts the non-overlapping area of the printed circuit board,
A screwing hole is provided in the second base so as to communicate with the through hole,
An electronic device characterized in that the printed circuit board is fixed on the heat dissipation member by penetrating a screwing member from above the printed circuit board to the through hole and screwing the screwed hole into the screwed hole;

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